The long range goal of our research program is to continue to use modern neuroanatomical tracing methods to analyze, in significant detail, the organization of central visual pathways in mammals. Specifically, cats and monkeys will be the primary experimental animals, with other mammals being used for comparative investigations. Specifically, the major thrust of our research endeavors for the next five years will focus upon defining basic connectivity patterns of the superior colliculus. These studies will be carried out at both the light and the electron microscope levels. We also plan to continue our connectional studies of visual centers which are closely related to the superior colliculus. Such areas include the retina, the pretectum, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, and the medial terminal nucleus. Finally, we also propose to analyze the connectivity of cortical areas 17 and 18.